What Does Caffeine Do to Your Brain? Here’s What’s Going on During Your Daily Cup of Coffee

Like a lot of people, I have a (bad) habit of reaching for a cup of coffee when I’m feeling a little sluggish or sleepy during the day. But have you ever stopped to wonder what all that caffeine is actually doing to your brain? I haven’t, but that’s probably because no one has ever been able to explain it to me in such a way that I could actually understand it. But hey, guess what? We’ve finally got a few answers, and what’s more, they actually make sense to scientific laypeople like myself.

Business Insider recently put together a neat-o little video that explains exactly what goes on in your brain when you introduce caffeine to your system. Fun fact: It turns out that caffeine doesn’t actually give you energy; rather, it tricks your brain into thinking you’re not tired by disguising itself as a different compound that naturally occurs in your brain — then booting that compound out of its rightful seat. Sneaky, no? Also, does anyone else have a mental image of a Game of Thrones-style battle occurring in their brain as one compound — Caffeine the Pretender — attempts to forcibly take over the spot that should be occupied by the One True Compound? No? Just me? OK then. Never mind.

1. First, let’s talk about adenosine.

Adenosine is a compound that naturally builds up in the brain while you’re awake. As it builds up, it bonds to receptors in your cells, which eventually gives you the cue of feeling tired.

2. So what’s caffeine got to do with it?

As luck (or, y’know, science) would have it, caffeine is remarkably similar in structure to adenosine. You can probably guess where this is heading, can’t you?

3. This is your brain on caffeine…

When you drink a cup of coffee (or soda, or tea, or Monster, or whatever), the caffeine in the drink travels through your blood stream up to your brain. Once it gets there, it bonds to the receptors that would normally be occupied by adenosine, stopping your brain from getting the “slow down” signals the adenosine would have given it. The substitution also causes your blood pressure and heart rate go up.

4. …And this is your brain on caffeine a few hours after the fact.

Eventually, though, the caffeine will loosen from the receptors, allowing the adenosine back in. After about six hours, you’ll only feel about half the effects of your caffeinated beverage of choice — and when you wake up in the morning, you’ll actually be experiencing symptoms of withdrawal. That’s when you’ll probably reach for the first cup of the day again, and, well… I believe the words “vicious” and “cycle” apply.